Automatic interlocking system



Feb. 12, 1935. E. M. ALLEN AUTOMATIC INTERLOCKING SYSTEM Filed Jan. 23, 1932 By Qm/ R 9 m H m A V M m l m \Nv E N% K? w bkw 1 N w k Rfifi EL iu Q q s a K i -B g B Q Q SN Q RI ME N J n \w w B J J H H w n In v MW m U @QU fid N W 1% E Na 1 w @v V m m? q. 1 m w% kw ww w a H16 A TT ORNE Y.

Patented Feb. 12, 1935 TENT: 50 FIFICE AUTOMATIC INTERLOCKIING SYSTEM Earl.M. Allen, .Swissvale, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation ofPennsylvania V Application January 23, 1932; Serial No. 588,2'i5

5 Claims.

My invention relates to apparatus for auto matic interlocking systems for governing traffic at grade crossings, and particularly to automatic interlocking systems governing trafiic at a grade 5 crossing of two railways. A feature of my inventionlies in the provision of simple and reliable apparatus for governing-the traffic of two railways that cross at grade at the intersection of two highways by the same signals that are'normally used to govern the-usual highway traffic; the

apparatus being so arranged that preferenceis given to the traffic on the railways over that'on the highways. It will be-lunderstood, however,

I do not wish to confine myself to railways crossing at grade at a highway intersection, but my invention is equally adapted to other grade crossings used by two difierent classes of traffic, one of which is to be given preference over the other at the intersection. .Other features of my invention will appear as the specification progresses.

I will describe one form of appartus embodying my invention, and will then point out the novel features thereof in claims. V r r Y Theaccompanying drawing is a diagrammatic view of one form of apparatus embodying my invention applied to a grade crossing at which two railways cross at grade at the intersection of two highways or streets. The highway traffic isnormally governed atthe intersection by the usual traflic light signals, which signals also serveto govern all railway traffic over the grade crossing.

Referring to the drawing a city street A is traversed by a railway C, and a city street Bis occupied by a street railway D,- the two railways crossing each other at :grade at the street intersection. Each railway is a single track line on which trafiic normally moves'in either direction. Whilemy invention is equally well adapted to all railways irrespective as to what propulsion power they may use, I shall refer to railway C as a high speed interurban line and railway D as an electric street railway line. To 'aid in the understanding of this description, I shall consider 'railwayC as an east and west road with eastbound traffic moving from the left to the right in the drawing, and westbound trafiic from the right to the left. The railway D will be spoken of as the north and south road with northbound traflic moving from the r bottom to the top in the drawing, and southbound traffic moving from the top to the bottom.

Highway traffic is governed at the intersection of streets A and B by four traffic light signals, one located at each corner and identified by the reference characters H, J, K, and L. Signal His set to govern trafiic moving east on street A, and signal J is set to governtraflic moving west on street A. In a similar. manner, signal L governs northbound trafiic on street B, and signalK governs southbound traffic. These same signals will be (Cl. 24s 114 utilized also, as willlater appear; for governing all railway traflic over the crossing. While these colored lights designated by the reference char: 5

acters G. Y, and R,with an exponent corresponding to the signal. The display of the green light G indicates that .traflic may move, the yellowllight Y indicates that the direction of traffic is about to be changed, and the display of 'a red light R requires all traffic to stop. As is'the usual practice, the control of these signals is so synchronized that they change colors in step with each other. For example,..when signals H and J 'each display a green light to permit 'east and westbound traflic to move on'street A, the signals'K and L each display a red light to stop all traflic onstreet B. When signals K. and L display a green light to permit trafiic' to move on street B, the signals H and J will ,each'display a red light to stop all 20 traflic on street A. vAll signals display a yellow light between the changingfrom the green to red or from the red to green to indicate that the directionfof trafiicis aboutto .bechanged. The significant'point in the operation 'of these traflic signals is that each will display a green light for a predetermined interval of time and then a red light for a predetermined interval of time and the display of green signals on one street takes place at the same time that the red signals are being exhibited on the opposite street. The changing of the signals from one color to the other is in accordance with a prearranged cycle of operation. For railway trafl'ic, the display of a green light is. a proceed signal for a train to move over the crossing and the display of a red light is a stop signal. 7 i I 1 The controlling element to establish the above cycle of operation for the trafiic light signals may be one of many types and is designated in the drawing as a whole by the reference character CR. The time element device CR includes a motor 10 that drives through a proper train of gears, not shown, a shaft indicated by the dotted line 11. Rigidly mounted on shaft 11 are three circuit controlling drums or cams 12, 13 and 14. The

drum 12 is provided with a raised portion 15 adapted when engaging 'a contact spring 16 to raise that spring into engagement. with a contact 1'7. When the drum 12 is rotated in a manner tobe later described sothat the raised portion 15 ismoved out of engagement with the contact V 18, 19, and 22 are so positioned with respect to."

away from the contact 21. In a like manner,'the drum 14 is provided with a raised portion 22 adapted, when brou'ght' yinto' engagement with a contact spring-23, td-rais'e the spring into engagement with a contact 24. The raised portions 1 5,

each other on their respective drums 12,113, and

14 that starting from the position shown in the drawing the raised portion. 15 occupiesthe. first 120 of the circumference t'aken a counterclockwise direction, the raised portion 18 thenext 60, the raised portion 22: the: next 120, and the raised portion 19 the last 60 of the circumference of the drums. It follows that in rotating the drum s frgorn the position shown in the drawing in" a clockwise 'direction,'.'as' indicated by arrows,

the contact 1617willbel lclosed and contacts 20: 21'.,and -23'\ 24 opened during the first 120 movement. During the. nextfiof of a rotation, contact 20-21 will be closedfan'd contacts 16- -17 and123-24 opened; During the next 120 of a rotation, cor'rtac'zt 23 -24 willhe closed, and contacts '16 1.'7 and 20--21 opened. 'Duringthe last venient source of current such as a common H voltalternating current'light circuit, along wire 25, contact1617, wire 26, and th'ence to the sig-v nal lights GK, GE, R and Rlin'parallel'andto the opposite terminal CX of ,the1 volt source. In order to simplify the drawingfas much as possible that it may be more easily understood,these lightcircuits-are not individually shown on the drawing, but indicatedby'r'eierence characters only. The'contact 20'21 is included in'an operatingcircuitthat extends from the BX terminal of the current source to the'Y lights ofeach of thesignalsas will be'readily understood-byan inspection of the drawing. The contact 2324- controls anpperating'ci-rcuit from: the terminal 7 BX'to'the wir e'27 from which point it; branches to the signalsG GKR and R -jin parallel, and

thenceto the opposite terminal CX'. It follows that, starting from the time thedrums 12,13,

and'li occupy the positions shown-in the drawing and during the first 120 of a rotation, the green lights G of signals K and L are illuminated to permit traftlc on street B, and the red lights R of signals :H and J are illuminated to stop traffic on street A. During the'ne'xt 60of a rotation, he yellow lights Y of each signalare illuminated to indicate to all'trainc that the direction of traflic'is about to be changed. During the next 120 of a'rotation, the green lights G of signals H and J and the red lights R; ofsignals K and L are displayed to permit trafific to move on street A and to stop trz'ifii'c on street B. During the last 60 of a rotation; the yellowlights are again displayed. This operating cyclein' the control of theti'aflic light signals will be'repeated' each revolution of the drums 12; 1-3, and 14, as long" as the motor 10 is energized to rotate theshaft 11. V

The railway C is: arranged into two track sections 12 and'34 by the usual insulated rail joints 5. Each track section is provided with a 7 track circuit including a sourceof' current such, for example; as the secondary 6 of a common track transformer T and one winding of an interlocking relay TR. As shown in the drawing, the winding 7- ofxthe interlocking reIay'f'TR is connected to the track section l--2 and its -winding-8 to the track section 34., As is common practice, the "armatures 30 and 31 controlled by the windings 7 and 8, respectively, are so interlocked by the interlocking feature, not shown, of the relay TR that'when either-armature is dropped full-down into engagementwith its back contact, it preventsthe remaining "armature from dropping far enough to-engage-its back contact even though the associated winding becomes deenergized. The interlocking mechanism, when thus operated, further prevents the said remaining armature from engaging its back contactwhile the winding which controls'the remaining armature continues deen ergized, even if the first armaturepicks up. Relay TR may be or any of a number of forms'of this well known" type, one ,of which is shown and described in Patent No. 799,452; entitled fRelay, issued September 1 2;,1905', t'oWgW. Coleman. :Associated with the interlocking relay is a relay 28 that is energizedbyvirtue of a circuit that can be traced from the BX'terminal through wire '25, contact 239-24, wires 27 and -29-j'winding of relay'28, either'back contact of armature 30 operated by the winding '7 of relay TR or the back contact of armature 31 operated by the'winding 8 of-the relay'TRyand' thence to the OK terminal of the current'sourcer Normally both windings? andB of the interlocking relay TR are energized,-and the ,circuit'tothe relay 28:held open even though the"contact"23-24 is intermittently closed bythe operation'of'the time element device CRHAn' eastboundtrain entering track section 1'2 will shunt winding '7 to drop armature 30 into engagement" with 'its back contact-and thus when" the contact 23"'24 is next closed, the relay 28-will become energized. As this eastbound train "proceeds towards "the crossing and then enters the section 3-4, the shimting ofithe winding'8 of the interlocking relay TR willno't'cause armature 31 to drop into engagement with its back contact due tothe fact that it is prevented from doing so by 'the'armature closed in .the' operationof: the time'element device CR.v As this westbound-train enterssection 1-2 and shuntsthe winding 7', armature 30is'prevented from dropping'far enough toi-engage its back contact with the result-thatrelay 28 becomes deenergized as soon as the: westboundtrain: vacates the section 3 4. :That isflj train onroad C approaching the crossing ,from. either direction will cause the relay 28 to become energized, but as a train recedes from the crossing in either directionfthe relay 28 becomes deenergized as soon as. the train has cleared the crossing; 'Thedirectional control exerted by the relay TR will appear when the operation of theapparatus described, I

On the' electric street railway D, the directional control is established by means of two trolley contactors 32 and 33. These trolley contactors may be any one of many types, several of' which are wellknown to the art. -In the formhere illustrated, the contact plates 35 and 41 of the trolley contactor 32 are located close to but insulated from the trolley wire 34. As'the trolleywheel of a car passes the contactor 32, it will engage first one plate and then the other depending upon the direction in which the car is moving; In a like manner, the trolley wheel of a car will engage the contact plates 43 and 48 of the contactorv 33'. As a northbound car approaches the crossing, its trolley wheel will first make contact between the trolley wire 34 and the contact plate 35, and current will flow from the trolley wire 34 through the trolley wheel and plate 35, and thence along wire 36, back contact of armature 37 of a relay 38, winding of relay 39, and to the ground connection 40, to energ'me relay 39, it being understood that the trolley wire 34 is connected to one terminal of a generator, not shown, whose other terminal is connected to ground in the usual manner As the trolley wheel'leaves the contact plate 35 and engages the contact plate 41, current is supplied to the relay 39 by the circuit that includes the front'contact of its own armature 42 to hold that relay energized until the northbound car has advanced far enough that'the trolley wheel moves away from the contact plate 41 at which time the relay 39 becomes deenergized. The trolley wheel of a southbound car moving away from the crossing will first make contact with the contact plate 41 of contactor 32 so that current flows from the trolley wire 34 through the wheel and plate 41, back contact of armature 42 of relay 39, winding of relay 38, and to the ground connection 40 to energize relay 38. Relay 38 is then held energized while the trolley wheel engages the plate 35 by the circuit that includes the front contact of armature 37 as will be readily understood by an inspection of the drawing. p

A southbound car approaching the crossing will have its trolley wheel first engage the contact plate 43 of contactor 33 with the result that current is suppliedfrom the trolley wire 34 through the plate 43 and the back contact of armature 44 of a relay 45 to the winding of a relay 46 and thence to a ground connection 47 to energize the relay46.r As-the trolley wheel engages the contact plate 48, relay 46 is retained energized through the front;contact of its own armature 49. When a northbound car travels away from the crossing, its trolley wheel will first engage the contact plate 48 of contactor 33, and the relay 45 becomes energized by current flowing from the trolley wire 34 and the plate 48 through the back contact of the armature 49 of relay 46, winding of the relay 45, and to the ground connection 47. Relay45 is then held energized while the trolley wheel engages the contact plate 43 by the circuit that" includes the front contact of its ownarmature 44. It follows that for a southbound car,the relay 46 associated with the trolley contactor 33 is energized, as the car approaches thecrossing, and the relay 38 associated with the trolley contactor 32 isrenergized as thecar travels away from the crossing. For a northbound car, the relay- 39 is energized as the car passes the contactor 32 in approaching the crossing, and the relay 45 is energized as the car passes contactor 33 in travelling away from the crossing. While trolley contactors have been used in connection with traflic on road D to determine the direction of travel, it will be understood that I do not wish to limit myself to trolley contactors but that track circuits and an interlocking relay such as described in connection with road C couldequally as well be used. As a matter of fact, myinvention is not limited to any specific manner of determining the direction of trafiic, and any standard method may be employed, several of which are well known. I.

Associated with the directional relays 38, 39, 45, and 46 is a stickrelay 50; The relay 50 is normally retained energizedby a stick circuit that extends from the positive terminal B1 of a convenient source of current, not'shown, back contact of armature 51 of relay 46, wire 52, back contact of armature 53 of relay 39, front contact of its own-armature 54;;resistance 68, winding of relay 50, and to the negative terminal 01 of the same source. of current." Relay 50 can be picked up by either of two circuits, one .of which. is from the terminal Blrthrough front'contact of earmature 55 of relay45, Wire 56, resistance 63,.winding ofrelay 50, and tothe negative terminal C1. The second pickup circuit isfrom terminal B1 through front contactor armature 57 of relay 38, and thence as before traced. It is clear, therefore, that relay 50 will become deenergized whenever a northbound car approaches the crossing and causes relay 39 to'be picked up opening the back contact of armature-.53 in the stick circuit for relay 50, or when a southbound car approaches the crossing causes the relay 46 to be picked up opening theback contact of armature 51 in the stick circuit'for relay 50 As a northbound car travels awayfrom the crossing and causes'relay 45 to be picked up to close the front contact of armature 55 or when a southbound car travels away from'- the crossing and causes the relay 38 to be picked-up to close the front contact of armature 57, the relay 50 will be reenergized. That is to say, by means of the trolley contactors 32 and 33 and the associated directional relays, a caronroad' D approaching the crossing will 'deenergize the stick relay 50 and the relay will stay down until the car has passed over the crossing and is travelling away from the crossing at which time therrelay 50 will be reenergized. The relay 50 controls, in turn, a relay 58 that is providedrwith an energizing circuit fromv the terminal BX through wire 25, contact 16-17, wires 26 and 59, winding of relay 58, wire 60, back contact of armature 61 of relay 50, and to the terminal CX.

The operating circuit for the motor 10 of the time element device CRis controlled jointly by the relays 28 and 58.- This operating circuit can be traced from the terminal B1 through the back contacts of armatures 62 and 63 of 1 relay .58 in parallel, wire '64, back contacts of armatures 65 and 66 of relay 28 inparallel, wire 67, motor 16, and to the terminal C1. Itfollows that as long as both relays 28 and 58 remain deenergized, the motor 10 is active to operate the drums 12, 13 and 14 in the manner previously pointed out, but with no train-approaching'on eitherroad Cor D.

With road C free from traflic, the interlocking relay TR is picked upholding the circuit to relay 28 open and that relay is' deenergized. With no trafiic on roadD within the limits of the trolley contactors 32 and 33, the relay 50 is held energized and the relay 58 is deenergized by its circuit being'held open at the back contact of armature 61 of relay 50. As pointed out above, with both relays .28. and 58 deenergized, the operating circuit to the motor '10 is completed and the motor active to rotate'the drums 1-2, 13, and 14 at a uniform rate resulting in the controlof signals H, J, K, and'L in such a'manner ithat highway trafic is permitted to proceed .first on street A and then on street B. I

. Assuming now thatan' eastbound train enters the track section. 12 andshuntsthe winding 7 of relay TR to drop armature 30 into engagement with its back contact: The; next timedrum 14 isoperated around to where it closes the contact 2324, the relay 28-becomes energized and picking up itsarmatures 65 and .66 opens the operating circuit to the motor 10. The operation of the device GR is now stoppedwith the drums 12, 13, and 14 so positioned thatthe contact 23-24 is closedand the contacts 2021 and 16-17 are both open. Contact 23+24 being held closed, the circuits to the green light G of. signals H and J and to .the red lights of signals K and L are closed, andthesesignals. are continually displayed- The .displayof the green light ofthe signal H permits the eastbound train to advance towards the crossing; and the display of the red lights of signals Kand L acts to stop not only the highway tramc on street B but to stop anycar approaching theintersectionion the. railway D. As the eastbound train proceeds over the crossing and enters the track section 3-4, winding 8 of the interlocking. relay TB is shunted but its armature 31 is prevented from-dropping into contact with its back contact by the interlockingfeature of this relay. The vacating of the section 1--.2 by the eastbound train, permits winding 'l'to become reenergizedgand the relay 28, in turn, deenergized, with the result that the motor is again started into operation and the normal operation of the tramc signals H, J, K, and L resumed. s

A westbound train approaching the crossing will shunt winding 8 causing its armature 31 to engage its back contact. With armature 31 fulldown, the relay 28 is picked up the next time the contact 2324 is closed in the normal operation of the device CR. Againjthe motorlOis stopped at a position where the contact v23-24 .is closed, and the contacts -'-21 and 16'1'l are both open. Thus the circuits to the green lights of signals H and J and to the red lights of signals K and L are continuously held;.closed,. and the westbound train permitted to advancextowards the crossing while all north and southbound trafficis stopped. Armature 31 being in its fulldown position, thearmatureis prevented from dropping: into engagement with its backcontact as the westbound train entersthe section 12 and shunts the winding ,7 of relay TR. Relay 28 is thus deenergized as soon as the section 3-4 is vacatedby the westbound train and the winding 8 of relay TR reenergized. The deenergizing of relay 28 closes the circuit to motorlO andthe normal operation of the'si gnals isresumed under the control of the time element device CR.

A northbound car passing the trolley contactor v 32 will operate the relay 39 in the manner pointed out above to open the stick circuit of relay 50 to deenergize that relay. The next time drum 12 is rotated around to where it closes the contact 15-17, the relay 58 is picked up to open the motor circuit at the back contacts of itsarmatures 62 and 63. r The device CR being stopped at a point where the contact 16,-17'is heldclcsed; thesignals K and L each display a green light, and the signals H and J ared light. Traflic being thus established for the roadD; the northbound car can advance. over the crossingiwhile all east and westboundtraffic both highway and railway are stopped.- ,f The northbound car on passing the trolley contactor 33 as it moves away from the crossing operatesthe relay to close the pickup W circuit for relay 50, and that relay is reenergized. As soon'as the relay is picked up, relay 58 becomes deenergized and the normal operation of the device CR re-established.

A southbound car approaching the crossing will operate the relay 46- as it passes the trolley contactor 33 to open the stick circuit for relay 50 with theresult that. the relay 58 is energized the next time the contact 16-17 is closed in the normal operation of. the. time element device CR. Again signals K and Leach display a green light, and the signals H and J va red light. The southbound. car passing the: trolley contactor 32 as it 'moves away from the crossing, operates relay 38 to reenergize relay 50 and,- in turn, deenergize relay '58 to re-establish the normal operation of the device C'. It is tobe noted that after a car or train enters upon the approach limits, the traffic signal will be held in the clear position for that particular car or train from the time that the clear signal is automatically displayed by the normal operation of the time element device until after the car or train has passed over the crossing. In

other words/after the signal has been fixed in the clear position; as the result of a train or car entering within the approach control, the time element device isrendered inactive until the car or train has advanced'over the intersection. The principle being that the train or car will automatically retain the green light for the signal governing traflic in the direction of its travel and relay 50 to become deehergized- As the device OR is nowheld stationary with contact 2 324 closed and contact 16--1'I open, the signals H and J remain green, and the signals K and L red, thereby permitting the eastbound train to advance over the crossing but stopping the southbound car even though it has acted to select the direction of traflic. As soon asthe eastbound train vacates the section 1 -2 and clears the crossing, the relay 28 is deenergized and the-motor I0 started. The time element device CRwill be operated around to the point'where thecontact 16-17 is closed at -;which time the relay '58 will be picked up as the relay 50is now downhavingbeen deenergized as the southboundcar passed the trolley contactor 33. Dev-ice 'CR' being this time stopped where contact 16'17 is'held closed, the signals K and L display a green light, and the signals H and J a red light. Thus the southbound car can advance over the intersection immediately after the eastbound trairi has'passed. As the southbound carpasses the contactor 32, the normal operation of 'the device CR is reestablishe'd in the manner previously described.

The operation of the "apparatus for traflic in other directions-will 'be similar 'to that already pointed out, and it is thought that it needs no further description. 7

The apparatus here disclosed provides simple and reliable means for controlling a set of signals adapted to govern trafiic through the intersection of two traiiic routes on which two different classes of trafiic travel. The signals are normally operated in a manner to accommodate a second class of trafiic which, in this instance, is highway traific by alternately setting the signals first for one route and then for the other route. Traffic of the first class of traific which, in this instance, is railway trafiic, is given preference in that the normal operation of the signals .is stopped and the route set to permit the advancing of trafi'lc on the route in which the trafl'ic of the first class is approaching the intersection. The approach of traffic of the first class on both routes results in the signals being cleared for the route on which the first class trafiic has first entered the approach limits. As soon as the trafiic on this first route has cleared the intersection, the signals are automatically changed and preference is given to the first class traific on the other route.

Although I have herein shown and described only one form of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track intersected by a trafiic route, railway signals for governing traffic movements on said railway track across said traffic route, trafiic signals for governing traffic movements on said traflic route across said railway track, a timing device, means for normally energizing said timing device, means controlled by said timing device for clearing said traffic signals alternately with said railway signals while said timing device is energized, and means controlled by a train on said railway track for deenergizing said timing device for retaining said railway signals in the clear condition when said train is approaching said traific route from either direction and for causing said timing device to become energized when said train crosses said trafiic route and also for preventing means controlled by said train from deenergizing said timing device while said train is receding from said traffic route.

2. In combination, a stretch of railway track intersected by a trafiic route, railway signals for governing trafiic movements on said railway track across said traffic route, traffic signals for governing traffic movements on said trafiic route across said railway track, a timing device, means for normally energizing said timing device, means controlled by said timing device for clearing said traffic signals alternately with said railway signals while said timing device is energized, and means controlled by a train on said railway track for deenergizing said timing device for retaining said railway signals in the clear condition when said train approaches within a given distance in either direction from said trafi'ic route and for causing said timing device to become energized when said train crosses said traflic route and also for preventing means controlled by said train from deenergizing said timing device when said train recedes to said given distance from said trafiic route.

3. In combination, a stretch of railway track comprising a first track section and a second track section one end of which is adjacent a given end of said first track section, a traffic route intersecting said railway track near the adjacent ends of said first and second track sections, an interlocking relay comprising a first and a second control winding, a track circuit forsaid first track section including the rails of said first track section and said first control winding as well as a source of current, a track circuit for said second track section including the rails of said second track section and said second control winding as well as a source of current, a timing device, means for normally energizing said timing device, railway signals for governing trafiic movements on said railway track across said traific route, traffic signals for governing traffic movements on said trafiic route across said railway track, means controlled by said timing device for clearing said trafiic signals alternately with said railway signals while said timing device is energized, and means controlled by said interlocking relay for deenergizing said timing device for retaining said railway signals in the clear condition while a train in either of said track sections is approaching said trafiic route and for energizing said timing device while a train is receding from said traffic route.

4. In combination, a stretch of railway track intersected by a trafiic route, a timing device, means for normally energizing said timing device, railway signals for governing trafiic movements on said railway track across said traffic route, trafiic signals for governing trafiic movements on said traffic route across said railway track, means controlled by said timing device for clearing said trafiic signals alternately with said railway signals while said timing device is energized, and means controlled by said timing device and by a train on said railway track for deenergizing said timing device for retaining said railway signals in the clear condition when said train is approaching said traffic route from either direction and for afterwards energizing said timing device and preventing its subsequent deenergization by said train while said train is receding from said trafilc route in either direction.

5. In combination, a stretch of railway track intersected by a traific route, a timing device, means for normally energizing said timing device, railway signals for governing traffic movements on said railway track across said traffic route, traflic signals for governing trafiic movements on said traffic route across said railway track, means controlled by said timing device for clearing said trafiic signals alternately with said railway signals while said timing device is energized, a pair of train controlled directional relays one of which becomes energizedonly when a train in a given direction from said traflic route is approaching said trafi'ic route and the second of which becomes energized only when a train in said given direction from said trafi'ic route is receding from said traffic route, a second pair of train controlled directional relays one of which becomes energized only when a train in the opposite direction from said traific route is approaching said trafiic route and the second of which becomes energized only when a train in said opposite direction from said trafilc route is receding from said trafic route, means controlled by the first relay of each of said pairs for deenergizing said timing device, and means controlled by the second relay of each of said pairs for energizing said timing device. 

